The invention concerns a motor vehicle windshield wiper comprising a spring for generating wiper pressure. The invention concerns more particularly a motor vehicle wiper comprising a driving head designed to be fixed to a free upper end of the wiper shaft at a bore, and containing a wiper arm which is articulated onto the driving head by a rear longitudinal end, around a transverse axis which is substantially perpendicular to the general longitudinal axis of the wiper and perpendicular to the driving shaft axis, between a raised position and an operative position towards which it is returned by a helical compression spring inserted between the driving head and a support surface of the arm.
In such a wiper, the wiper arm has at its front longitudinal end, a wiper blade equipped with a wiping scraper designed to come into contact with the window to be wiped. The wiping scraper is produced from a supple material and it is, for example, carried by a structure articulated to the blade in a manner that it can hug the curve, as long as it is convex.
In addition, so that the wiping scraper closely hugs the curve of the window, it is necessary that the wiper arm exerts a wiping pressure on the blade in order to press the scraper against the window, the pressure being assured by a wiping pressure spring which pulls the wiper arm towards its operative position.
According to a traditional idea of a wiping pressure spring, this spring is created in a helical tension spring form which is hung by the first end on the arm and by the other end on the driving head along a longitudinal movement line such that, when the arm is near its operative position, the spring pulls the arm in such a manner that the spring presses the scraper against the window, and, in opposition, when the arm is close to its raised position, the spring acts on the arm in order to support it in a means of propping up which defines this raised position.
According to such a conception of a wiper, it is thus necessary to plan that the rear part of the wiper arm be sufficiently large in the transverse direction to be able accommodate the helical tension spring which, in addition, is generally of a relatively long length.
In addition, it had already been proposed in document DE-A-35.08.542, for example, a wiper of which the arm contains a rear part covering the driving head articulated around a transverse axis constructed to the front of the driving head in relation to the driving shaft onto which is mounted the head, and in which a compression screw is constructed to the rear of the driving head in order to cooperate with a supporting surface of the arm which extends above the screw in order to move the arm into rotation around its articulated axis on the driving head towards the operative position.
Such an arrangement notably presents the inconvenience of extending, in an significant manner, the driving head towards the rear, that is to say, to the opposite of the really useful part of the wiper. This is so much more cumbersome that it is necessary to take into account the fact that this longitudinal offshoot towards the rear possesses an angular clearance in rotation around the axis of the driving shaft equal to that of the wiper, which makes it necessary to plan a corresponding clearance space.
The object of the invention is to propose a new conception or means of imposing a wiping pressure to the wiper blade, these means allowing the conception of the most compact wiper possible.
In addition, the object of this invention is to propose, in the frame of a wiper containing a wiping pressure spring which works by compression, means which allow keeping the wiper arm in a raised position, especially in order to facilitate the act of replacing the wiper blade.